Method and apparatus for spontaneous fire extinction in tanks of combustible or inflammable liquids



OR 394159323 SR A Dec. 10, 1968 3,415,323

P. AJOVALASIT METHOD AND APPARATUS FOR SPONTANEOUS FIRE EXTINCTION IN TANKS 0F COMBUSTIBLE OR INFLAMMABLE LIQUIDS Filed July 21. 1966 2 Sheets-Sheet 1 l/VVENI'OR MEMO AJ'OVALASIT LJzm /Mu ATTORNEY 5 United States Patent METHOD AND APPARATUS FUR SPONTANEOUS FIRE EXTINCTION IN TANKS 0F COMBUSTIELE 0R INFLAMMABLE LIQUIDS Pietro Ajovalasit, 57 via Niccolo Turrisi,

Palermo, Italy Filed July 21, 1966, Ser. No. 566,939 Claims priority, application Italy, July 28, 1965, 16,877 65 9 Claims. (Cl. 169-1) ABSTRACT OF THE DISCLOSURE A method and apparatus for extinguishing fires in tanks which contain combustible liquids. The liquid in the tank is withdrawn from the region of the surface of the liquid and re-introduced into the tank at the region of the base thereof so that the hotter liquid at the top of the tank is mixed with the colder liquid at the bottom thereof, and in addition it is possible to direct the liquid through coo-ling devices prior to re-introduction of the liquid into the base of the tank. A suction means is capable of progressively withdrawing the liquid from the interior of the tank at theregion of the surface of the liquid, and a conduit means receives the liquid from the suction means and directs it back into the tank at the region of the base thereof.

It is the object of the present invention to provide a novel method and apparatus allowing fire extinction of combustible or inflammable liquids in tanks, particularly large sized tanks.

The main object of the present invention is to provide a method and apparatus allowing extinction to be achieved by physical action without any use of special or particular extinguishing materials, such as foams, inert gasses, powders and the like. Accordingly, it is to be considered that heretofore fire extinction of combustible or inflammable liquids has been achieved by covering the surface of the same with special materials, the function of which is to separate said surface from room air. Among the most commonly used materials there are: 'foa-rns of various types, carbon dioxide, inert gasses, extinguishing materials and the like. Such materials have serious drawbacks and disadvantages, such as: high cost, unstability, and poor heat resistance, difficulty for effectively distributing then on surfaces of large tanks the area of which can be even some thousands of square meters.

The method of the invention is based on the fact that in order to take fire, combustible liquids have to be turned into vapour, and that the higher the liquid temperature, the larger this transformation is. On the other hand, in a burning liquid there is a hot surface layer in contact with the environment, in which flames develop, the layer providing the combustion required vapours, while the underneath liquid mass has surface-to-bottom decreasing temperatures. Accordingly, if surface zone in a burning liquid is cooled, as temperature of the latter falls, vaporization will decrease and hence degree of combustion until complete extinction.

The method according to the invention is characterized, therefore, in that extinction of combustible or inflammable liquids is achieved by cooling the surface layers of such liquids, so as to minimize vaporization thereof.

According to a first embodiment of the invention, the method consists of sucking the liquid from the hot surface layer and passing it through refrigerating equipment to lower the temperature thereof prior to admitting it again inside of said tank.

According to another variant of the invention, which Patented Dec. 10, 1968 may be used in case large bulks of liquid are within the tank, readmission is not preceded by cooling since this is attained by mixing the drawn liquid with the cold liquid at the tank base.

The invention will be better understood from the following detailed disclosure, given by mere way of example and thus of not limitation, of a preferred embodiment shown in the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of a device embodying the method of the invention, associated to a cutaway tank wherein the combustible or inflammable liquid is contained;

FIG. 2 is a plan view of the device of FIG. 1;

FIG. 3 is an enlarged vertical sectional view of a portion of the device according to the invention and associated tank.

Referring to the figures, a conventional tank is indicated as a who-1e at 1, within which tank a bulk of combustible or inflammable liquid 2 is contained.

Inside of the tank, preferably at axis thereof, there is disposed an intake device, indicated as a whole at 3 and formed of a series of tube sections 4, 5, 6, 7, 8 and 9, telescopically joined to one another. In other terms, the various elements 4 to 9 are capable of a relative telescopical movement so that, as hereinafter will be more apparent, such elements can provide a conduit, the height .of which will correspond in any moment to level 10 of the liquid within the tank.

The uppermost tubular element 4 is connected at its upper end to a truncated cone or funnel-shaped part 11. To such a funnel-shaped part there are secured in known manner any of the substantially triangular shape plates 12 spaced apart from one another so that passages for liquid travel from tank to inside of device 3 are provided between the plates. At the other end, the plates are connected in any known manner to an annular float 13, formed, for example, of an internally hollow sealed metal body. Such a float can, as described, be integrally formed, that is to form a continuous ring, or carried out in various mutually articulated parts.

Besides of metal, the float can be formed of expanded plastics material. Extension of float 13 can be made equal to the whole surface 10 of the liquid within the tank in order to limit contact with air of such a surface, hence to reduce vaporization and therefore accelerate extinction.

At the lower end, section 4 has an outwardly directed flange 14 intended to engage with a hook-shaped flange 15 at the upper end of section 5 to provide for dragging of said last section when level of the liquid within the tank increases. An annular seal 16 of a substantially L shape is interposed between the two flanges.

At its lower end, section 5 has a flange 17 completely similar to flange 14 of section 4. Such a flange co-operates with the flange provided at the top of section 6 and which is identical to flange indicated at 15. Similarly, section 6 can be coupled with section 7, and so on.

The last section, indicated at 9, is rigidly secured with its contour flange to a perforated plate 18, at its upper end carried by a cylindrical body 19 secured at its lower end to the bottom 20 of tank 1.

The inner chamber defined by cylinder 19 and plate 18 is connected to a pipe 21, sealingly passing through the wall of tank 1 and arriving at a suction means in the form of a pump, indicated as a whole at 22, and namely at the suction or intake side of the same. The pump is driven by any known motor, not shown, which may be incorporated within pump itself. The delivery side of the pump branches into two conduits 23 and 24- which are connected to a cooler 25. Said cooler is a conventional cooler, forming for example pipe-type heat exchanger, wherein the cooling fluid can be water entering fitting 26 and emerging from fitting 27.

After cooling incooler 25, the combustible or inflammable liquid arrives at conduits 28 opening into the bottom of the tank, for instance at two diametrically opposite positions, at A in FIG. 3.

Thus, the liquid is drawn from the hotter layers where evaporation is higher, and is cooled in coolers 25 and readmitted into the low part of the tank.

Should the tank be of a large capacity, coolers 25 can be dispensed with. In such a case, cooling will be achieved by mixing the hotter surface layers as drawn from pump 22 with the deeper and hence colder layers of liquid in the tank.

The length of intake device 3 will automatically accommodate to the level existing from time to time in tank 1 as a result of float 13 being present.

According to an embodiment variant of the invention, the telescopic tube may be replaced by a flexible hose, whenever allowed by nature of liquids, which will be connected at the top to a float and at the bottom to a conduit leading to the suction side of the pump.

Thus, it will be seen that with the method and apparatus of the invention the combustible or inflammable liquid within the tank is withdrawn at the region of the surface of the liquid from the interior of the tank by way of a suction means and is re-introduced into the tank in the I region of the base thereof through a conduit means such as the conduits 28. The liquid which is circulated in this way can be cooled by cooling means 25 interposed in the conduit means 28.

Whenever allowed by nature of liquid in the tank, the device of the invention may intergrate with an action of atomized water jets operating on the liquid. This can be attained arranging nozzles 30 on the top of tank 1, said nozzles being intended for causing atomization of the water conveyed to such nozzles through pipes (not shown), with the eventual aid of pumps.

Water being obtained in the form of droplets will vaporize subtracting heat from Warm environment, and by gradually taking the place of air will finally exert also a choking action which contributes to accelerate extinction.

I claim:

1. A method for extinguishing fires in tanks which contain combustible liquids, comprising the steps of Withdrawing liquid from the interior of the tank at the region of the surface of the liquid therein, and re-introducing the thus withdrawn liquid back into the tank at a base region thereof where the liquid is colder, so that the surface 4 region of the liquid in the tank is cooled by mixing with the colder liquid at the region of the tank base for reducing vaporization of the liquid in the tank.

2. A method as recited in claim 1 including the additional step of cooling the withdrawn liquid before it is reintroduced into the tank.

3. The method of claim 1 and including the additional step of directing atomized jets of Water onto the surface of the liquid in the tank.

4. In combination with a tank containing a combustible liquid, fire-extinguishing apparatus comprising suction means communicating with the interior of the tank at the region of the surface of the liquid therein for withdrawing liquid out of the interior of the tank from the region of the surface of the liquid in the tank, and conduit means communicating with said suction means to receive the withdrawn liquid therefrom, said conduit means also communicating with the tank at a base region thereof for re-introducing the withdrawn liquid into the tank at the base region thereof.

5. The combination of claim 4 and wherein a cooling means coacts with the liquid flowing through said conduit means for cooling the liquid.

6. The combination of claim 4 and wherein said suction means includes a float for floating on the surface of the liquid in the tank to accommodate the suction means to the elevation of the surface of the liquid.

7. The combination of claim 6 and wherein said float covers the liquid surface at least in part.

8. The combination of claim 6 and wherein said suction means further includes at least one flexible hose connected with said float.

9. The combination of claim 6 and wherein said suction means includes at least one telescopic tube which is connected with said float.

U.S. Cl. X.R 169-4 

